The last time I worked on a wheel bearing on a full sized Chevy truck I could have sworn the weight was under a pound. And that's a truck designed for severe duty. The bearings seems like an odd place to try to reduce mass when there are far more important areas to address first like a lightweight rotating assembly inside the engine or the structure/body of the car and so on.

That said, its all about the money you wish to spend, loads applied, and durability you need. Exotic materials cost a lot to procure and manufacture with precision, an average auto is going to have 3x the mass of an F1 car so that's going to scale the loads tremendously, and an F1 car is rebuilt every 500 miles.

Do you have a specific application like a high fuel mileage competition car or some other highly weight critical application? Because for something like that with light usage, extremely low weight, low rolling resistance, etc where the weight of the bearings would contribute significantly to the car than some of the hi-performance motorcycle parts would be an easy and economical choice.

The performance of these motorcycles in the last couple decades is amazing and one of the few affordable means of enjoying the fruits of racing. The new bikes are lighter, stiffer, faster - better performers in every way and yet the entire purchase costs less than the cost of one automotive option filtering down from F1. Oh, and they can get you from point A to point B too.